Chap. II. CLASSIFICATIONS OF ACALEPIIS. 143 



genuine Acaleplis, and should be united, not only with the naked-eyed Medusce, but 

 also with the Siphonoj)horre. There also I traced the special homologies of the Cte- 

 nophorjB and other Acalephs, and the general homologies of all Radiata, including 

 the Echinoderms. There I advocated the. compound character of the Siphonophora?, 

 and carried that view even further than it is carried by some naturalists, showing, 

 what I believe to be true, that certain parts of their communities, which are still 

 considered by some anatomists as organs, are in reality distinct individuals. 



I do not make this somewhat extended reference to my " Lectures," in order 

 to substantiate special claims of priority, but solely to prevent any imputation of 

 having borroAved from others the views I have derived from my own investigations, 

 and uj^on which I may have to dwell more fully in the course of this work. 

 This appears to me the more necessary, since the reports of my lectures have 

 had only a very limited circulation in Europe. 



We are inde))ted to Liitken for valualjle contributions to the natural history 

 of the Acalephs of Greenland and Scandinavia, in connection with which he has 

 published a new systematic arrangement of the naked-eyed Medusa?. As I know 

 this paper only from the abstracts given by Leuckart in the Archiv fiir Natur- 

 geschichte for 1854, 2d vol., p. 424, I abstain from further remarks about it. 



LUTKEN'S CLASSIFICATION OF THE NAKED-EYED MEDUSAE, 18o0. 



1st Group. 1st Family. iEginea? : Carybdea, Eurybia, Cunina, JEgina, ^giiiopsis, Polyxenia. 



2d CTi'oup. 1st Family. JEquoreada: : JEquorea, Mesonema, Stomobracliium, Thaiimantias. 



2d Family. Oceanida; : Oceania, Saphenia, Turris, Modeeria. 



3d Family. Bougainvilleas : Bougainvillea, Lizzia, Eathkia. 



4tli Family. Geryonidae: Geryonia, Tima, Geryonopsis, Diana^a, Circe. 



5th Family. Sarsiada; : Sarsia, Slabberia, Steenstruppia, Eiipbysa. 



3d Group. 1st Family. Wills iada; : Willsia, Proboscidactyla, Berenice. 



Milne-Edwards never attempted systematically to present his views of the 

 affinities of the Acalephs in the form of a sj)ecial classification, though we owe 

 to him important contributions to the history of this class. Von Siebold, in his 

 textrbook of comparative anatomy, has adopted the classification of Eschscholtz, 

 which, to this day, is followed by most naturalists. 



Since, judging from my observations upon Millepora, a large number of Corals 

 must be considered as belonging to the type of Hydroids, it is necessary to intro- 

 duce here the classification of Corals by Milne-Edwards, in order more directly to 

 show what changes are likely to be rendered necessary in the systematic arrange- 

 ment of the Corals, in consequence of my discovery of the acalephian affinities 

 of the genus Millepora. 



